Process of making milling cutters



P. F. VOKAL ET AL 1 PROCESS OF MAKING MILLING CUTTERS May 5,1925; 1,536,736

Filgd May 24 1921 Patented Ma 5,1925.

' uNlTEnfsTA'T s PATENT] o FicEg i PAUL r. voKA AND ALBERT w ERDMAN, or nanrronn, conmzcrronr, AssrcNoas ro PRATT & WHITNEY COMPANY, on NEW Yonx, N. 2., A conro-narron on NEW JnnsnY.

Application filed gra a4,

To all whom it may concern:

Be it known that we, PA'ULF. VOKA and, ALBERT W. ERDMAN, citizens of the Umted States, and .residents of Hartford, in the county of Hartford and State of Connecticut, have invented certain new and useful Improvemen s inProcesses of Mak ng l\:I1ll-. ing Gutters, of 'which the followmg is a specification. U A

' Our invention relates to process of forming milling cutters and particularly to process of forming milling cutters havinghehcally arranged teeth. g '5 I One object of our invention is to provlde a simple and eflicient method of operatlng rotating tools toform a milling cutter that shall have teeth that are so relieved alongpredetermined lines as'to permit the grinding'of the teeth along the front cutting faces without changing the form of .the artlcle cut by the cutter: w Another object of our invention is to pro .vide a method of the above indicated character that shall consist in simultaneously forming flutes and relieved teeth on a blank by means of aformed milling cutter which is rotated in engagement with the blank which is fed axially, in grinding the relieved surfaces of the teeth on the cutter blank by means ,of a concave formed grinding wheel, and in grinding the cutting faces of 'the teeth in conformity with the form of the teeth. a h n A The milling cutters which are produced by preliminary milling. cutters 'in accordance with the method now practiced are not pro vided with relieved'teeth of such form as to permit the sharpening of the cuttersby merely grinding the front cutting faces of. the teeth. The customary method of sharpening plain milling cutters is to grind the' peripheral faces of the teeth. After repeatedly regrinding the peripheral faces of the teeth the relievedsurfaces back of such rnocnss or alan ne MILLING cnrr'nes.

1921. Serial no. 472,029.

cave face in L In a milling cutter formed in accordance withour invention, the teeth are' sharpened by grinding the front cutting faces without altering or changing the relieved or peripheral faces. Thus. the sharpening of the cutter is efl'ected by a simple operation and the chip space between the teeth is increased by such operation. Moreover, duced in accordance with our-method are provided with teeth having convex relieved surfaces. which are preferred.

In the accompanying drawing:

Figure 1 is an elevational view of a milling cutter formed invention.

Fig.2 is an end.vie.w of the milling cutter shown in Fig. 1-. i i

Fig. 3 is a partial end view of the millin cutter shown in Figs. 1 and2 enlarged, and compared with another millingcutter.

Fig. 4 is a diagrammatic view illustrating the step of forming the teeth with helical flutes therebetween. v

Fig. 5-is' a diagrammatic view illustrating the step of grinding the front cutting faces of the teeth.

' Fig. 6 is a-diagrammatic view illustratthe cutters proin accordance with our ing the step of grinding the relieved surfaces ofthie teeth.

Referring to the drawing a milling cutter 1', formed in accordance with our invenhelicoidal'surfaces and may be ground for Extending back-- sharpening the cutter. .wardly from the front cutting faces are relieved surfaces 5 which preferably follow -a spiral. Figs. 1 and 2 is provided with non-radially arranged cutting faces, it is to be under-' stood that our process is equally applicable for producing a cutter having radially arrangedfcutting faces. -,Moreover, the teeth of the cutter may follow the axis thereof Although the cutter shown in.

instead of being inclined as shownin the illustrated cutter.

' Referring to Figs. 4, 5' and .6, the process for'forming a milling cutter. willbe described. The first step of shaping a. blank to produce a milling cutteris preferably effected in a universal milling machine. blank. The blank 7 is given a movement of However, other machines are equally aprotation in accordance with the inclination plicable for effecting such step. A formed of the teeth relative to the axis thereof.

milling cutter B is rotated in engagement Referring to Fig. 3 'of the drawing, a mill with acutter blank7, the cutter blank being ing cutter formed in accordance with our given a movement of rotation corresponding invention is compared with a plain milling to the inclination of the teeth with respect cutter formed in accordance with the usual to the axis. Preferably the cutter blank method. A milling cutter 13 formed in acis moved axially to effect feeding movements] cordance with the usual methods is indicated between the blank and the cutter. The by dotted lines as also is a grinding wheel formed milling cutter 6 is provided with an 14 for grinding the peripheral surfaces of extended portion 8 on each tooth which cuts the teeth of such a cutter. As shown in Fig.

the flutes 3 between the formed teeth 2 as 3,-the teeth of the usual plain milling cutter shown in Figs. 1 and 2. Adjacent to the have-their peripheral faces ground by a projecting portion 8- on the teeth is a con- Wheel which rotates on an axis parallel to the cave surface 9 which serves to "cut the relief axis of the cutter blank. Such an operation on the teeth of the blank. The shape of the produces a concave peripheral surface on teeth on the cutter 6 may be varied to proeach tooth as is indicated in Fig.3 of the duce any desired flutes between the teeth and drawing. Moreover, theusual plain milling to form, any desired relief on the teeth. The cutter cannot be sharpened by grinding the axis of the milling cutter, in the customary front cutting face of each tooth but is manner, is maintained perpendicular to the 1 sharpened by grinding the peripheral face desired helix'angle of the teeth and not to. of each tooth as above indicated. The grinda plane through the axis of the blank. Con= ing of the peripheral face of the usual plain sequently, unlessacorrection is made to the milling cutter by a wheel which rotates on form of the cutter, the relief lines on the an axis parallel to the axis of the blank reteeth of the blank will be perpendicular to duces the chip space between the teeth in-. the helix angle which is not desired. The stead of increasing such space as is desired. form of the milling cutter is changed some- In a milling cutter formed in accordance what to compensate for any distortion of thewith our invention, the teeth are uniformly relief lines that may be caused by therelative relieved as indicated in Fig. 3 of the drawposition of the blank and the milling cutter. ing and the cutter may be sharpened by Theterm spiralrelief which is set forth grinding the front cutting face 4. The in many of the claims is intended to .cover sh'arpemngor grinding of the front cutting any relieved surface which extends backface is efi'ectedby the step of the process ward from the frohtcuttingface and inillustrated in Fig. 5 of the drawing. When ward toward the axis of the blank. After the teeth are sharpened by grinding the the relieved teeth are formed on the cutter front cutting faces, it will be noted the chip blank, it is subjected to a hardening process. space is increased in place of being decreased "When the blank has been hardened, the as in the case of a milling cutter formed in front cutting face is ground by a wheel 10' accordance wlth the usual methods. as shown in Fig. 5 of the drawing. Such operation may be formed in agrinding ma-. various steps may be made within the spirit The blank is rotated in accordance with the chine such as disclosed in the patent to and scope of our invention and such modi- -Frieclerich Muller, No. 1,338,320, dated fications are intended to be covered by the April 27th, 1920. The grinding wheel 10 is appended claims. rotated in engagement with the blank 7. What we claim 1s:

1. The process of forming amilling cutinclination .of the teeth relative to the axis ter which consists in cutting teeth and a radial cuttingfaces.

and is fed axially past the wheel 10. The spirally relieving the surfaces thereof in a grinding wheellO may be set to grind the cylindrical blank by means of a formed millteeth in conformity either to radial or noning cutter, in grinding the relieved surfacesof the teeth by a formed grinding wheel The relieved surfaces of the blank are which is so shaped as to maintain the spiralground by a step which is diagrammatically ly relieved surfaces, and in sharpening the illustrated in Fig. 6 of the drawing. Such teeth by grinding the front cutting faces. step may beperformed by a grinding ma- 2. The process of forming a milling cutchine such as disclosed in the Miiller patent ter which consists in cutting helical teeth referred to above. In inding the relieved spirally relieving the surfaces thereof in a surface of the teeth of the blank, the grindcylindrical blank by means of a formed mill- 1 ing wheel 11 is rotated on an axisperpendicing cutter, in grinding the relieved surfaces ular to the plane of the helix of the cutter of the helical teeth by a formed grinding teeth. lhe grinding surface 12 of the wheel wheel which is so shaped as to maintain the 11 is concave in form and is so shaped as to spiral relief on the teeth, and in sharpening cut any desired relief on the teeth of the the teeth by grinding the front cutting faces.

3. The process of forming a milling cut- I ter which consists in effecting feeding movement between a formed milling cutter and a blank not only to cut the flutes between the teeth but also to effect spiral relief on the teeth by one cutter, and in grinding the relieved surfaces and the front .cutting faces of the teeth.

4. The process of forming a milling cutter having helically inclined teethwhich consists in rotating a blank in accordance with the desired angle of the helix while effecting feeding movement between a formed milling cutter and the blank not only to cut helicalflutes but also to effect relief on the teeth formed between the flutes, and in grinding the relieved surfaces and the front cutting faces of the teeth.

5. The process of forming a milling'cutter having helical flutes which consists in rotating a blank in conformity to the desired helical angle of the flutes, in rotating a formed milling cutter in engagement with the blank, in effecting feeding movement between theformed milling cutter and the blank to form helical flutes and teeth having spirally relieved surfaces, in hardening and tempering the blank, in grinding the relieved surfaces of the teeth by aformed grinding wheel having a concave grinding surface so constructed as to maintain the spiral relief on the teeth, and in grinding the front cutting face of-the teeth in accordance with the spiral form of the teeth.

6. The process of forming a milling cutter having lfelically arranged undercut teeth which consists in rotating a blank in accord? said surfaces lying in planes perpendicular to the axis of-the blank, vin grinding the relieved surfaces of the teeth by a grinding wheel having a formed concave grinding sur face, said blank being moved along the wheel in conformity to the helix angle of the teeth,

and in grinding the front cutting faces of the teeth in accordance with the helical inclination of the teeth.

In testimony whereof, we hereto affix'our signatures.

-PAUL F. VOKAL. ALBERT W. ERDMAN. 

